Thermo-electric humidity instrument.



E. W. COMFORT.

THERMO ELECTRIC HUMIDITY INSTRUMENT.

APPLICATION HLED YES. 1, 1909.

1,169,617. Patented Jan 25, 1916.

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E. W. COMFORT.

THERMO ELECTRIC HUMIDITY INSTRUMENT.

APPLICATION man FEB. 1. 1909.

1,169,617. Patented Jan. 25, 1916.

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THERMO ELECTRIC HUMIDITY INSTRUMENT.

APPLICATION FILED FEB. 1, 1909.

1,169,617, 4 r Patented Jan. 25, 1916. [7 5 gm.

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E. W. COMFORT.

- THERMO ELECTRIC HUMIDITY INSTRUMENT.

APPLICATION FILED FEB. I, 19 09.

1,169,617. I Patented Jan; 25, 1916.

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EDWARD COMFORT, OF BUFFALO, NEW YORK, ASSIGNOB '10 B'O'FFALO FORGE COMPANY, OF BUFFALO, NEW YORK.

.THERMO-ELECTRIC HUMIDITY TNSTR'UMEN'I'.

To all whom it may concern:

Be it known that I, EDWARD W. COMFORT, a citizen of the United States, residing at Buflalo, in the county of Erie and State-of New York,have invented a new and useful Improvement in Thermo-Electric Humidity "Instruments, of which the following is a specification. I The dry and wet bulb temperatures of th atmosphere are equal when the air is saturated, or has a humidity of one hundred .per I cent., but for all percentages of humidity below saturation there is a difference between the wet and dry bulb temperatures,

this*diflerence, or wet bulb depression, at

"humidity of one hundred per cent., which current will be proportional to the wet bulb.

depression, so that changesin the humidity of the air can be indicated by a device for measuring this current. If the dry bulb temperature of the air remained constant it would only be necessary to connect a delicate milliammeter properly calibrated to the thermoelectric pile to accurately indicate percentages of humidity. As, however, the wet bulb depressions for the same percentage of humidity change with fluctuations in the actual, or dry bulb, temperature of the air it is-necessary, in order to indicate the percentages of humidity under ordinary atmospheric conditions, to make provision for varying the electric current in response to changes in'the actual temperature of the air. The hygrometric charts show that for any given percentage of :humidity above, say twenty per cent., the wet bulb depressions vary by a practically constant difierence for equal changes in the dry bulb tem-.

perature, and consequently means are provided for increasing or decreasing the cur? rent in proportion as the dry bulb temperature lowers or rises. This can be done in different ways, for example, by automatically increasing or decreasing the resistance Specification of Letters Patent.

Application filed February 1, 1909. Serial No. 475,539.

Patented Jan. '25, 1916.

in the electrical circuit inproportion as the temperature uses or falls by means controlled by a thermostat, or by automatically varying the number of couples in the thermoelectric pile by a thermostatic device to decrease or increase the voltage of the electric current in proportion to increments or decrements in the temperature.

The object of the invention is to produce an eflicient instrumentof simple construction in which a thermoelectric battery is utilized to operate a device by which the hygrometric condition of the arr can be either indicated, recorded or regulated.

In the accompanying rawings, consisting of three sheets: Figure 1 is an elevation, partly in section, of a humidity gage or indicator'embodyin the invention. Fig. 2 is a sectional elevation, on an enlarged scale, in'line 2-2, Fig. 1, of the rheostat. Fig. 3 is a longitudinal sectibnal elevation of the thermoelectric battery; Fig. 4 is a transverse section of the thermoelectric battery in line. 4-4, Fig. 3. F-igJ5 is an elevation of a humidity indicator of modified construction. Fig. 6 is a plan view thereof omitting the indicating device. Fig. 7 is an elevation of the thermoelectric pile employed in the instrument shown in Fig. 5. Fig. 8 illustrates diagrammatically ahumidity regulator adapted to be actuated by thermoelectrical means.

Like letters of reference refer to like parts in the several figures Referring first to the instrument shown in Figs. 1-4, A represents a thermoelectric battery and B anelectric current measuring inder whereby they are retained in position and insulated from each other. a is a shell or casing inclosing the conduetors. This shell is open at one end and the ]l1IlCt10IlS of the couples at this end of the battery are" exposed to theyactual or dry bulb temperature'of the air. a represents a wick or piece of absorbent -material which inc-loses the other end of the battery and is kept wet by dipping into water in a receptacle a whe by the junctions at this end of the batter;

are influenced by the lower wet bulb temperature of the air. The battery is supported on a suitable insulating base (1 provided with binding posts a a which connect the terminals of the battery and of the external circuit C C.

The current measuring device B can be a delicate milliammeter or galvanometer of ordinary construction except that the scale is suitably calibrated to indicate percentages of humidity preferably ranging from twenty per cent. to one hundred per cent.

1) represents a rheostat which, in the construction shown, comprises a cast iron receptacle (l party filled with mercury, and a disk d of suitable insulating material which is adapted to revolve in said receptacle and has a series of peripheral contact points d", Fig. 2, connected by a resistance wire d the coils or loops of which are embedded in the disk. The disk 03 is secured to a shaft d journaled at opposite ends in adjustable bearings e e. One end of the resistance d is connected to the shaft (5 of the disk, see Fig. 2. The shaft bearings are both insulated from the mercury receptacle, but one of the bearings, e, and the mercury receptacle are electrically connected with binding posts 6 6 respectively, by which the rheostat is connected in the battery circuit C C? so that the circuit is completed through the resistance A thermic motor E of well known form, consisting of acoiled bar composed of two strips of metal having different coeiiicients of expansion, is attached at opposite ends to the rheostat shaft d and to a fixed part of the rheostat frame. This bar is subjected tothe dry bulb'temperature of the air and a rise in the temperature'will cause it to change form and rotate the rheostat shaft and disk in a direction to lift the contact points d successively, out of the mercury, while a fall in the temperature will cause the disk to rotate in the opposite direction and successively immerse the contact points inthe mercury, thus increasing or decreasing the resistance in the battery circuit and consequently modifying the current in proportion to changes of temperature. Variations in the humidity and also the temperature of the air therefore mutually influence the operation of the current measuring instrument B in such manner that it accurately indicates the percentage of humidity of the air. 4

The described operation of the instru ment is, of course, not dependent upon the described construction of either the thermoelectric battery, the means for causing its opposite junctions to be infiuenred respectively by'the dry and wet bulb temperatures of the air, the rheostat, the thermic motor for operating the rheostat, or the current measuring. device, and either of these devices may be of any suitable construction capable of cooperating to indicate humidi ties when combined as described.

Figs. 5-7 illustrate a modification of the apparatus, in whlch, in place of a rheostat for increasing and reducing the circuit resistance to compensate for changes in temperature, thermoelectric couples are subtracted from or added to the battery for decreasing or incrcasingthe electric current 1n proportion to changes of temperature.

tially as before described,'but a larger number of couples is required than is shown in the drawings to make the instrument operative for a wide range of temperatures. As the operation of the apparatus is only dependent on changes of voltage the couples can be made of finewire and a' large num-. ber can be used. The battery is preferably arranged vertically with its lower junctions inclosed by the wetted wick A and contact devices F are provided at its upper junctions preferably consisting of past iron cups containing mercury and floating contact points. G represents a thermic motor which consists of a coiled compound bar, such. as

'before described, fixed at one end and'having a contact shoe at its free end adapted ,to move from one to the other of the contact devices F which a are arranged below the path of movement of the shoe. The circuit conductors hh for the galvanometer are connected by binding posts h and 715- respectively to the first thermoelectric couple of the battery and to the fixed end of the thermic motor G. If the actual temperature of the air affecting the motor G lowers, the contact shoe will be moved in a direction to add couples to the battery and increase its voltage in proportion to the fall in temperature, while if the temperature rises, the shoe will be moved in the opposite direction to cut out couples from the battery and decrease its voltage in proportion to the rise in temperature. The operation of the galvanometer B in this construction, like that in the first apparatus described, is

therefore responsive to both changes in the application of the in-' out of contact with these bars.

-';ections.

ammeter or galvanometer before used is shown, but a stationary contact bar 1 and two adjustable contact bars 2 and 3 are provided over which the index B of the instrument swings, the index being normally The bars 2 and 3 are separated by a gap and are mounted on a plate I which is adjustable to change the position of said gap relative to the humidity scale. 2' is a pivoted bail which is oscillated by a clock work or other motor 11' to intermittently press the index B against the contact bar 1 and one or the other of the contact bars 2 and 3, depending upon the adjustment of said bars and the position of the index. K represents the controlling valve or device of an apparatus for increasing ordecreasing the humidity, and K and K two solenoids or electrical detices for moving said valve in opposite di- The solenoids are both connected by the conductor of an electrical circuit to the contact bar 1 and are connected by circuitv conductors k and 70 respectively to the contact bars 2 and 3.

If it is desired to maintain a humidity of fifty-five per cent, for example, the contacts 2 and 3 are set .as shown, with the gap between them opposite the fifty-five per cent. mark on the scale. So long as the humidity remains at fifty-five per cent., the index being over the gap, the circuit cannot be closed through either of the solenoids and the regulating device will remain inactive. A decrease in the humidity will cause the index to swing over the contact bar 3 so that the circuit will be intermittently closed through the solenoid 12 which will move the regulating device K- to increase the humidity again, whereas if the humidity rises above fifty-five per cent. it will cause the index to swing over the contact bar 2 so that the circuit will be intermittently closed through the other solenoid 70 which will move the regulating device K to decrease the humidity. Any desired percentage of humidity can be maintained by adjusting the plate I to set the gap between the contact bars 2 and 3 opposite to the mark on the scale indicating such humidity. Other suitable regulating means could be used in place of those described.

I claim as my} invention:

1. The combination of a thermoelectric battery, one junction portion of which is influenced by the dry bulb temperature of the air, means for subjecting another junction portion thereof to the Wet bulb temperature of the air, a device operated by the current generated by said battery, and a device for altering said current in response to changes in the dry bulb temperature of the air, substantially as set forth.

2. The combination of a thermoelectric battery, one junction portion of which is influenced by the dry bulb, temperature of perature of the air, a humidity indicating device operated by the current generated by said battery, and means for altering said current in proportion to changes in the dry bulb temperature of the air, substantially as set forth.

3. The combination of a thermoelectric battery, one junction portion of which is influenced by the dry bulb temperature of the'air, means for subjecting another junction portion thereof to the wet bulb temperature of the air, a device connected in circuit with said battery and operated by the current generated by the battery, and a device for automatically varying the resistance in said circuit in proportion to changes in the dry bulb temperature of the air, substantially as set forth.

4. The combination of a thermoelectric battery, one junction portion of which is influenced by the dry bulb temperature of the air, means for subjecting another junction portion thereof to the wet bulb tem perature of the air, a humidity indicating device connected in circuit with said battery .and operated by the current generated by the battery, a rheostat for varying the resistance in said circuit, and a thermic motor for operating said rheostat, substantially as set forth.

5. The combination of a battery composed of a group of thermoelectric couples arranged with opposite junctions at opposite ends of the battery, a wick surrounding one end of said battery, means for wetting said wick, a device operated by the current generated by said battery, and a device for automatically altering said current in proportion to changes in the dry bulb temperature of the air, substantially as set forth.

6. The combination of a thermoelectric battery, one junction portion of which is influenced by the dry bulb temperature of the air, means for subjecting another -junction portion thereof to the wet bulb temperature of the air, a. humidity indicating device connected in circuit with said battery and operated by the current generated by the battery, 2. rheostat interposed in said circuit comprising a receptacle containing mercury, and a revolving body partly immersed in said mercury and having exposed contacts connected by resistance, and a thermic motor for revolving said. body to immerse more or less of said contacts, substantially as set forth.

'7. The combination of a thermoelectricbattery composed of a group, of thermoelectric couples, means whereby the opposite ends of said couples are influenced respectively by the dry and wet bulb temperatures of the air, and a humidity indicating device operated by the electrical current generated by said battery, substantially as set forth.

8. The combination of a thermoelectric battery, one junction portion of which is influenced by the dry bulb temperature of the air, means whereby another junction portion of said battery is influenced by the Wet bulb temperature of the air, indicating means which are moved by the current generated by said battery, a graduated scale cooperating with said indicating means to indicate the hygrometric condition of the air, and a device for altering said electric current in response to changes in the dry 1 EDWARD W. COMFORT.

Witnesses REENE,

WM. L. Fox. 

